fix($stickyState): Make sticky state compatible with UI-Router 0.2.12
fix($stickyState): Make sticky state compatible with UI-Router 0.2.12

- mock ParamSet.$$equals for SurrogateStates

Closes #88

Sharondio/ui-router-extras,phenomnomnominal/ui-router-extras,OpenWhere/ui-router-extras,christopherthielen/ui-router-extras,viewthespace/ui-router-extras,jurrinus/ui-router-extras,platdesign/ui-router-extras,Mindfor/ui-router-extras,hightower/ui-router-extras